Hand punch

Abstract

There is disclosed a hand punch comprising a C-shaped member having a punch and die mounted in the extremities thereof. A rotary head having a threaded member axially disposed therein is mounted for rotation in one extremity of the C and the punch or cutting head is mounted on that member so that, when the rotary head is rotated, the cutting head is advanced into the die. The cutting head has cutting edges adapted to bite into the material to be punched and to hold it against rotation. It is threaded onto the threaded member by a reverse thread so that, once it bites into the material to be punched, the threaded member is held against rotation, whereby rotation of the rotary head drives the punch into the die.

I claim: 
     
       1. In a hand punch comprising a base member, a die member comprising part of said base member, a cutter head complementary with said die member adapted to be driven into said die member in order to punch material disposed on said die member, the improvement which comprises:   a rotary head mounted in said base member coaxial with and spaced from said die member, said rotry head having a threaded axial bore and being mounted for in-place rotation relative to said base member;   a threaded member complementary with said threaded axial bore adapted to be threaded therein for axial movement when said rotary head is rotated relative thereto;   mounting means for mounting said cutter head on said threaded member in position such that axial movement of said threaded member causes said cutter head to move into and out of said die member;   cutting means on said cutter head for cutting into material to be punched, said mounting means and said cutting means cooperating to prevent rotation of said threaded member when said cutting means is engaged with the material to be punched,   whereby rotation of said rotary head causes said threaded member and the cutter head mounted thereon to move axially into said die and to effect punching of the material to be punched; in which said mounting means comprises a reversely threaded bore in said cutter head and a complementary reversely threaded portion at the bottom of said threaded member, whereby the tendency of said threaded member to rotate with said rotary head is counteracted as soon as said cutting means bites into the material to be punched; and in which a stop means is disposed between the threaded and reverse threaded portions of said threaded member, whereby when said cutter head is threaded onto the reverse threaded portion thereof, it jams against said stop means.   
     
     
       2. A hand punch of claim 1, in which said stop means comprises a jam nut adapted to be threaded on said reverse threaded portion. 
     
     
       3. In a hand punch comprising a base member, a die member comprising part of said base member, a cutter head complementary with said die member adapted to be driven into said die member in order to punch material disposed on said die member, the improvement which comprises:   a rotary head mounted in said base member coaxial with and spaced from said die member, said rotary head having a threaded axial bore and being mounted for in-place rotation relative to said base member;   a threaded member complementary with said threaded axial bore adapted to be threaded therein for axial movement when said rotary head is rotated relative thereto;   mounting means for mounting said cutter head on said threaded member in position such that axial movement of said threaded member causes said cutter head to move into and out of said die member;   cutting means on said cutter head for cutting into material to be punched, said mounting means and said cutting means cooperating to prevent rotation of said threaded member when said cutting means is engaged with the material to be punched,   whereby rotation of said rotary head causes said threaded member and the cutter head mounted thereon to move axially into said die and to effect punching of the material to be punched; in which said mounting means comprises a reversely threaded bore in said cutter head and a complementary reversely threaded portion at the bottom of said threaded member, whereby the tendency of said threaded member to rotate with said rotary head is counteracted as soon as said cutting means bites into the material to be punched; and in which said rotary head comprises upper and lower flange means to prevent axial movement of said rotary had and to limit the movement thereof to said in-place rotation.   
     
     
       4. A hand punch of claim 3 in which the lower flange is separated from said base member by a thrust bearing. 
     
     
       5. A hand punch of claim 3, in which said rotary member comprises upper and lower parts, one of which is threaded into the other; in which the part which is threaded into the other part has a shoulder adapted to abut the other part and in which the parts, when threaded together, constitute a unitary rotary head, and in which the bottom part is separated from the base member by a thrust bearing to ease rotation of the rotary head during the punching operation.